3I/ATLAS

Third Interstellar Visitor to Our Solar System

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MISSION CONTROL DASHBOARD

Next Milestone
Closest Approach to Earth
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Mars Encounter
Oct 3, 2025
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0.223 AU
Earth Encounter
Dec 19, 2025
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~1.8 AU
Jupiter Encounter
Mar 16, 2026
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0.265 AU
Distance from Sun
0.000
AU
Live Data
Distance from Earth
0.000
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Distance from Mars
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Distance from Jupiter
0.000
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Current Velocity
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Visual Magnitude
0.0
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Calculated
Surface Temperature
0
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Phase Angle
0.0
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Live Data
Journey Through Our Solar System 0.0%
Discovery Exit Observation
Current Velocity
137,000
mph
Distance Traveled
0.000
AU
Mission Elapsed Time
0d 00h 00m
since discovery
Orbital Eccentricity
6.14
(highest known)
Solar Radiation Flux
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W/m²
Estimated Coma Size
0
km

Motor de Búsqueda

View Physical Characteristics → View Timeline → View FAQs →

Overview

3I/ATLAS is the third confirmed interstellar object to pass through our Solar System, discovered on July 1, 2025, by the NASA-funded ATLAS telescope in Río Hurtado, Chile. This ancient visitor from beyond our solar system offers scientists a rare opportunity to study material from another star system. [NASA]

Since Closest to Sun

October 29, 2025

Closest to Earth

~1.8 AU minimum distance

Observation Window

Peak visibility period

Discovery Date

July 1, 2025

NASA

Speed

~137,000 mph

NASA

Age (estimated)

7.6 - 14 billion years

Wikipedia

Eccentricity

6.14 (highest known)

Wikipedia

Analytics Dashboard

Real-time data visualization and comparative analysis of 3I/ATLAS with other celestial objects

Current Distance from Sun
Live Data
Current Velocity
Live Data
Visual Magnitude
Estimated
Distance from Earth
Live Data

Distance from Earth Over Time

Speed Comparison

Orbital Eccentricity Comparison

Composition Analysis

Trajectory Path (AU from Sun)

Visual Magnitude Over Time

Interstellar Visitor Comparison

Solar Radiation Intensity

Solar flux (W/m²) drives sublimation and activity (Inverse Square Law)

Velocity Evolution

Speed changes due to gravitational acceleration near the Sun (Kepler's Laws)

Current Distance from Sun

Current Velocity

Size Comparison of Interstellar Objects

Coma Size Evolution

Gas cloud expansion driven by sublimation

Gravitational Energy

Energy exchange in hyperbolic orbit

Temperature & Solar Heating Analysis

Visualizing how solar heating affects 3I/ATLAS's surface temperature and activity as it approaches perihelion

Estimated Surface Temperature vs Distance from Sun

Temperature estimates based on blackbody radiation model. Actual surface temperature may vary based on albedo, composition, and rotation.

Gas Production Rates (H₂O, CO₂, CO)

Gas production calculated using sublimation physics. CO₂ dominates at large distances (sublimates at 20K), while H₂O requires higher temperatures (170K) and peaks near perihelion. Production scales with solar flux (∝ 1/r²⁻³).

At Discovery (3.2 AU)

~155 K

(-118°C / -180°F)

Low activity, minimal sublimation

At Perihelion (1.36 AU)

~238 K

(-35°C / -31°F)

Peak activity, maximum sublimation

Sublimation Zone

~183-238 K

Water ice actively sublimates

Distance: 1.36 - 2.3 AU from Sun

CO₂ Dominance

8:1 ratio

CO₂ to H₂O production

One of highest ratios ever observed

Advanced Scientific Analysis

Detailed physics-based analysis of 3I/ATLAS using orbital mechanics, thermodynamics, and observational astronomy.

Orbital Mechanics & Dynamics

Orbital Energy Components Over Time

Energy exchange between kinetic (KE = ½v²) and potential (PE = -GM/r) during hyperbolic trajectory. Total energy remains constant.

Radial vs Tangential Velocity Components

Vector decomposition of velocity: v_r (radial, toward/away from Sun) and v_θ (tangential, perpendicular to radius).

True Anomaly vs Time

Orbital position angle (θ) measured from perihelion. θ = 0° at closest approach to Sun.

Angular Momentum Conservation

Specific angular momentum L = r × v remains constant throughout orbit (Kepler's second law).

Thermal & Physical Evolution

Blackbody Radiation Spectrum at Different Distances

Planck curves showing thermal emission spectrum B(λ,T) at discovery (155K) and perihelion (238K). Peak shifts to shorter wavelengths as temperature increases.

Sublimation Rate vs Distance

Power-law relationship: Rate ∝ r^(-n) where n depends on sublimation temperature. CO₂ sublimates at 20K, H₂O requires 170K.

Surface Temperature Gradient (Day/Night)

Temperature variation across nucleus surface. Peak at subsolar point (noon), minimum on night side. Cosine distribution due to solar illumination angle.

Molecular Production Rates Timeline

Production rates Q (molecules/s) for CO₂, H₂O, CO, and CN. CO₂ dominates at large distances due to low sublimation temperature.

Compositional & Spectroscopic Analysis

Column Density Profiles

Gas distribution in coma: N(r) = Q/(4πr²v_exp). Density decreases as r^(-2) for spherical outflow.

Observability & Detection Planning

Apparent Size Evolution (Angular Diameter)

Angular size θ = 2×arctan(D/2Δ) for planning telescope resolution requirements. Nucleus ~20 km, coma ~40,000 km.

Signal-to-Noise Ratio for Different Telescopes

SNR ∝ D²×10^(-0.4m)×√t for 1-hour exposure. Larger apertures provide quadratically better SNR.

Radiation & Space Environment

Solar Wind Ram Pressure

Dynamic pressure P = ρv² shapes ion tail. Solar wind density n ≈ 5/r² cm⁻³, velocity v ≈ 400 km/s.

UV Radiation Flux

UV photons dissociate H₂O → OH + H (observed by Swift). Lyman-α (121.6 nm), UV-C, and UV-B components scale as r^(-2).

Scientific Methodology

All charts use physics-based calculations with verified formulas: Kepler's laws, vis-viva equation, blackbody radiation (Planck's law), sublimation physics, and observational astronomy principles. Data sources: mission-constants.js (orbital parameters), JWST observations (composition), Gran Telescopio Canarias (rotation period).

Interactive Solar System View

Real-time 2D view of 3I/ATLAS's hyperbolic trajectory through our solar system (view from above)

Note: This visualization is an approximation for educational purposes only. Distances, sizes, and orbital paths are not to scale and are simplified for clarity.

Oct 29, 2025
Sun
Mercury
Venus
Earth
Mars
Jupiter
3I/ATLAS

Current Positions

3I/ATLAS: Loading...
Distance from Sun: Loading...
Distance from Earth: Loading...
Distance from Mars: Loading...
Velocity: Loading...

Real-Time Tracking

Track the current position of 3I/ATLAS in real-time using official NASA/JPL data and interactive 3D visualizations.

NASA JPL Orbit Viewer

Official NASA orbit visualization tool showing 3I/ATLAS trajectory through the solar system.

Launch NASA Orbit Viewer Note: Search for "3I" or "C/2025 N1" in the small body field

TheSkyLive 3D Tracker

Interactive 3D solar system view with real-time position data from JPL Horizons.

Open 3D Tracker Real-time updates using official ephemeris data

Live Position Data

Current coordinates, distance, and speed from TheSkyLive's real-time tracker.

View Live Data Updated using JPL Horizons ephemeris service

Discovery & Timeline

June 14, 2025
Pre-discovery observations captured [NASA]
July 1, 2025
Official discovery by ATLAS telescope, Chile [NASA]
October 3, 2025
Closest approach to Mars [NASA]
October 29, 2025
Perihelion - Closest approach to the Sun (~1.36-1.4 AU) [NASA] [Wikipedia]

Name Breakdown: "3" indicates it's the third known interstellar object, "I" means interstellar, and "ATLAS" refers to the Asteroid Terrestrial-impact Last Alert System discovery telescope. [NASA]

Physical Characteristics

Size & Structure

  • Nucleus diameter: 0.44 - 5.6 km [NASA]
  • Estimated size: ~20 km wide
  • Rotation period: 16.79 ± 0.23 hours [A&A]
  • Type: Active interstellar object with visible coma and tail [ESA]
  • Orbital eccentricity: 6.14±0.001 (highest of all known interstellar objects) [Wikipedia]
  • Incoming velocity: 57.9763 ± 0.0044 km/s (~60 km/s relative to Sun) [arXiv]

Composition

  • Primary component: Unusually rich in carbon dioxide [Wikipedia]
  • CO₂/H₂O ratio: 8:1 (one of highest ever observed) [NASA JWST]
  • Water: Water ice, water vapor detected [NASA Space News]
  • Other gases: Carbon monoxide, carbonyl sulfide [ESA]
  • Spectrum: Red continuum with complex carbonaceous and irradiated organics [ApJ]
  • Activity: Releasing gases as it approaches the Sun [ESA]

Origin & Age

3I/ATLAS likely originated from the Milky Way's galactic thick disk during the "cosmic noon" period of intense star formation 9-13 billion years ago - potentially older than our Solar System itself. Scientists cannot trace it back to its original parent star, adding to its mystery. [arXiv]

Scientific Observations

Major Telescope Observations

Hubble Space Telescope

July 21, 2025

Captured images showing teardrop-shaped dust cocoon when comet was 277 million miles from Earth. Revealed clear activity with dust emission from Sun-facing side.

James Webb Space Telescope

August 6, 2025

Near-Infrared Spectrograph observations revealed exceptional CO₂/H₂O ratio of 8:1 - one of the highest ever observed in any comet. Also detected water ice, water vapor, CO, and carbonyl sulfide.

SPHEREx

August 7-15, 2025

Detected carbon dioxide gas in coma and found water ice in the nucleus.

Gran Telescopio Canarias

2025

10.4m telescope determined rotation period of 16.79 ± 0.23 hours. Physical characterization supports that extrasolar debris is similar to Solar System debris.

Gemini South Telescope

Ongoing

Observations showing increasing activity and lengthening tail as it travels through Solar System.

ESA Mars Orbiters

October 2025

ExoMars TGO (CaSSIS camera) and Mars Express captured images during Mars close approach on October 3, 2025.

Virtual Telescope Project

November 2025

Post-perihelion images by Gianluca Masi showing tail development after emerging from the other side of the Sun.

Observing Missions

NASA Missions [NASA]

  • Hubble Space Telescope
  • James Webb Space Telescope
  • Swift UV Telescope
  • SPHEREx
  • Mars rovers and orbiters

ESA Missions [ESA]

  • Mars Express
  • ExoMars Trace Gas Orbiter
  • Juice spacecraft

Key Scientific Findings

  • Unusual 8:1 CO₂/H₂O ratio - highest ever observed (JWST) [NASA]
  • Rotation period: 16.79 ± 0.23 hours (Gran Telescopio Canarias) [A&A]
  • Water detected by Swift telescope [NASA Space News]
  • Displays "extreme negative polarization" - unusual behavior [NewsBreak]
  • Red spectrum with complex carbonaceous and irradiated organics [ApJ]
  • Likely originated from galactic thick disk 9-13 billion years ago [arXiv]
  • Closest observations captured by ESA's Mars orbiters during Mars flyby [ESA]
  • Provides insights into interstellar object composition and star system formation
⚠ Safety Notice: 3I/ATLAS poses absolutely no threat to Earth. Its closest approach will be approximately 1.8 AU (about 170 million miles / 270 million kilometers) from our planet. [NASA]

Scientific Publications & Research Papers

Peer-reviewed research papers and arXiv preprints about 3I/ATLAS. This collection includes discovery papers, spectroscopic analyses, and theoretical studies from the global astronomical community.

arXiv Preprints (Self-Published)

Peer-Reviewed Journal Publications

Note on arXiv Papers: arXiv is a preprint repository where scientists share research before peer review. While not yet formally peer-reviewed, these papers represent cutting-edge research by leading astronomers and undergo community scrutiny. Many will eventually appear in peer-reviewed journals.

Latest News & Articles

Updates on Interstellar Comet 3I/ATLAS: NASA Images, Many Tails, and Non-gravitational Forces NEW

Sky & Telescope | November 20, 2025

Read article →

NASA releases close-up pictures of interstellar comet 3I/Atlas NEW

PBS NewsHour | November 19, 2025

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NASA releases new photos of interstellar comet 3I/ATLAS NEW

NBC News | November 19, 2025

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Interstellar comet 3I/ATLAS images released by NASA NEW

CNN | November 19, 2025

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Everything we know about 3I/ATLAS: The confirmed comet speeding through our Solar System NEW

Euronews | October 29, 2025

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Interstellar comet 3I/ATLAS and its ion tail - November 19, 2025 NEW

Virtual Telescope Project | November 19, 2025

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The 12th Anomaly of 3I/ATLAS: Orientation of the Jets is Not Smeared by Rotation NEW

Avi Loeb / Medium | November 2025

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NASA releases close-up images of interstellar comet making a rare flyby NEW

CBS News | November 2025

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'3I/ATLAS is a comet': NASA releases new images and addresses alien rumors NEW

Live Science | November 20, 2025

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NASA's STEREO Observes Interstellar Comet 3I/ATLAS NEW

NASA Science | November 19, 2025

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NASA/ESA's SOHO Observes Interstellar Comet 3I/ATLAS NEW

NASA Science | November 19, 2025

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Irradiated Comet 3I/ATLAS glows green and hides its tail in new image

Live Science | NEW

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Gravitational Lensing of 3I/ATLAS by the Sun NEW

Avi Loeb / Medium | NEW

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The Inspiration Delivered by 3I/ATLAS to Our Doorstep NEW

Avi Loeb / Medium | NEW

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No Clear Cometary Tail in Post-Perihelion Images of 3I/ATLAS

Avi Loeb / Medium

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Afterthoughts on the Non-Gravitational Acceleration of 3I/ATLAS at Perihelion

Avi Loeb / Medium

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3I/ATLAS Rapidly Brightens and Gets Bluer than the Sun Near Perihelion

Avi Loeb / Medium

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Interstellar object 3I/ATLAS, has just been targeted in a new campaign initiated by a United Nations-endorsed group focused on the defense of Earth against space objects

Minor Planet Center

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A Sunward Jet from 3I/ATLAS Imaged by the Two-Meter Twin Telescope

Avi Loeb / Medium

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ESA's ExoMars and Mars Express observe comet 3I/ATLAS

European Space Agency

Read article →

These robots on Mars and Jupiter are capturing images of comet 3I/ATLAS

BBC Sky at Night Magazine

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New Images of Nickel and Cyanide Around 3I/ATLAS from the Keck Telescope

Avi Loeb / Medium

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Comet or alien spaceship? An astrophysicist explains what we know about interstellar traveler 3I/Atlas

Northeastern University

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Interstellar comet 3I/ATLAS is losing water 'like a fire hose'

Live Science

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Swift's UV Telescope Reveals Water in Interstellar Comet 3I/ATLAS

NASA Space News

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Astronomers catch rare glimpse of interstellar comet 3I/ATLAS

ABC News

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European Mars orbiter spies interstellar comet 3I/ATLAS

Space.com

Read article →

Interstellar comet 3I/ATLAS carries water across the stars

Earth.com

Read article →

Interstellar comet passing by Mars seen in rare images

CBS News

Read article →

Data Sources & API

Real-Time Data Sources

All real-time orbital data and statistics displayed on this website are calculated using official data from:

  • JPL Horizons System - NASA's Jet Propulsion Laboratory provides highly accurate ephemeris data for solar system objects. Our calculations are based on orbital elements from this system.
    → Visit JPL Horizons System
    → API Documentation
  • Minor Planet Center (MPC) - The International Astronomical Union's clearinghouse for observations of asteroids, comets, and natural satellites.
    → Visit Minor Planet Center
  • TheSkyLive.com - Aggregates real-time astronomical data from JPL Horizons and MPC for visualization.
    → 3I/ATLAS Live Tracker

Data Update Frequency: Real-time statistics are recalculated every 5 minutes based on current date/time and latest orbital elements. Historical uptime of data sources exceeds 99.9%.

Videos

Scientific presentations, observations, and educational content about 3I/ATLAS

Official Resources & Links

Official Space Agencies

NASA

Official NASA Science page for 3I/ATLAS

Visit NASA Page →

ESA

European Space Agency FAQ and observations

Visit ESA FAQ →

ESA - ExoMars Observations

ExoMars and Mars Express observation details

View Observations →

Wikipedia

Comprehensive encyclopedia entry on 3I/ATLAS

Read on Wikipedia →

Astro Photons

The Third Interstellar Visitor Explained

Learn More →

Fascinating Facts

1st

First interstellar object detected with water by NASA's Swift telescope

3rd

Third confirmed interstellar object ever discovered (after 1I/ʻOumuamua and 2I/Borisov)

6.14

Highest orbital eccentricity of any known interstellar object

Older

Potentially older than our Solar System (up to 14 billion years old)

Frequently Asked Questions (FAQ)

3I/ATLAS (C/2025 N1) is the third confirmed interstellar object to pass through our Solar System. It was discovered on July 1, 2025, by the NASA-funded ATLAS telescope in Chile. The '3I' designation indicates it's the third interstellar object, 'ATLAS' refers to the discovering telescope.

No, 3I/ATLAS poses no threat to Earth. Its closest approach to Earth will be approximately 1.8 AU (about 270 million kilometers or 168 million miles) on December 19, 2025. For context, 1 AU is the distance from Earth to the Sun, so 3I/ATLAS will be nearly twice that distance away at its closest point. Its trajectory is well-understood and monitored by NASA.

3I/ATLAS requires a telescope to observe. During its brightest period (around perihelion in late October 2025), it reaches a visual magnitude of approximately 9.5-10, which requires at least a 6-8 inch (150-200mm) telescope under dark skies. Binoculars are not sufficient. The comet appears as a faint, fuzzy patch rather than a dramatic sight. Check the Live Tracking section for current sky position.

3I/ATLAS was discovered by the ATLAS (Asteroid Terrestrial-impact Last Alert System) telescope network in Río Hurtado, Chile on July 1, 2025. ATLAS is a NASA-funded early warning system designed to detect near-Earth objects. After the initial detection, astronomers calculated its orbit and confirmed its hyperbolic trajectory with an eccentricity of 6.14, proving it originated from outside our Solar System.

3I/ATLAS is extraordinary for several reasons:

  • Interstellar Origin: It comes from outside our Solar System, carrying material from another star system.
  • Highest Eccentricity: Its orbital eccentricity of 6.14 is the highest of any known interstellar object.
  • Water Detection: NASA's Swift telescope detected water vapor, making it the first interstellar object with confirmed water.
  • Ancient Age: Estimated to be 7.6-14 billion years old, potentially older than our Solar System.
  • Active Comet: Unlike the first interstellar visitor ('Oumuamua), 3I/ATLAS displays typical cometary activity with a visible coma and tail.

The peak observation window is around perihelion (October 29, 2025) when 3I/ATLAS is brightest at magnitude ~9.5-10. However, it remains visible with telescopes for several months before and after perihelion. The comet is best observed from the Southern Hemisphere initially, but becomes visible from Northern Hemisphere locations as it moves through the solar system. Use the Live Tracking tools to find its current position in the sky.

3I/ATLAS exhibits several anomalous behaviors that make it a unique target for scientific study:

  • Non-Gravitational Acceleration: The comet experiences unexpected acceleration near perihelion that cannot be explained by gravity alone. This 'outgassing rocket effect' from volatile sublimation is significantly stronger than predicted, suggesting unusual composition or internal structure. [Research by Avi Loeb]
  • Extreme Brightness Change: 3I/ATLAS rapidly brightened near perihelion and became bluer than the Sun in color - an unusual spectral shift that indicates extremely high surface temperatures and intense volatile activity not typically seen in comets. [Avi Loeb, Medium]
  • Sunward Jet: High-resolution imaging from the Two-Meter Twin Telescope revealed a prominent sunward-facing jet - a directional outgassing stream pointing directly at the Sun, which contributes to the non-gravitational forces and suggests asymmetric heating or surface features. [Two-Meter Twin Telescope Study]
  • Exceptional Water Production: NASA's Swift UV telescope detected water vapor production rates described as 'like a fire hose on full blast' - far exceeding models for a comet of its estimated size (0.44-5.6 km diameter), suggesting either a larger nucleus or unusually volatile-rich composition. [NASA Swift Observations]
  • Anti-Tail Reversal: The comet displayed an anti-tail (dust trail pointing toward the Sun) that subsequently transformed into a normal tail - a rare phenomenon indicating complex dust dynamics and particle size distribution in the coma. [Avi Loeb Analysis]
  • Exotic Chemistry: Spectroscopic observations from Keck Telescope revealed significant amounts of nickel and cyanide in the coma - chemical signatures that provide clues about the conditions in its birth star system and the comet's formation environment. [Keck Spectroscopy]

Scientific Significance: These anomalies make 3I/ATLAS an exceptional laboratory for studying interstellar material and comparing planetary system formation across different stars. The non-gravitational acceleration, in particular, is being closely analyzed by researchers including Harvard's Avi Loeb to understand whether it represents purely natural cometary outgassing or hints at more exotic physics.

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